TI bq25703A I2C Multi-Chemistry Battery Boost-Buck Charge Controller Solution

TI's bq25703A is an I2C multi-chemistry battery boost-buck charge controller with a system power monitor and processor thermal monitor. It has the advantages of low component count and high efficiency, and can be used from a variety of input sources. - 4 batteries to charge, input voltage 3.5V-24V, support USB2.0, USB 3.0, USB 3.1 (Type C) and USB_PD input current setting, seamless conversion of buck and boost operation. Output current up to 6.35A, Programmable switching frequency 800kHz or 1.2MHz, charging voltage ±0.5%, input / charging current ±2%, input / charging current monitoring ±2%, power monitoring ±5%. Mainly used in drones, Bluetooth speakers, IP cameras , detachable power supplies, tablets and power packs, industrial and medical equipment and handheld devices with rechargeable batteries. This article describes the main features of bq25703A, functional block diagram, typical application circuit diagram and evaluation module bq2570x EVM (bq25700AEVM-732 and bq25703AEVM-732 Main features, circuit diagrams, bill of materials and PCB assembly drawings.

The bq25703A is a synchronous NVDC battery buck-boost charge controller, offering low component count, high efficiency soluTIon for space-constraint, mulTI-chemistry battery charging applicaTIons.

The NVDC-1 configuration allows the system to be regulated at battery voltage, but not drop below system minimum voltage. The system keeps operating even when the battery is completely discharged or removed. When load power exceeds input source rating, the battery goes into supplement Mode and prevents the input source from being overloaded.

The bq25703A charges battery from a wide range of input sources including USB adapter, high voltage USB PD sources and traditional adapters.During power up, the charger sets converter to buck, boost or buck-boost configuration based on input source and battery conditions. Chargers automatically transits among buck, boost and buck-boost configuration without host control.

In the absence of an input source, the bq25703A supports On-the-Go (OTG) function from 1-to 4-cell battery to generate 4.48 V to 20.8 V on VBUS. During OTG mode, the charger regulates output voltage and output current .

The bq25703A monitors adapter current, battery current and system power. The flexibly programmed PROCHOT output goes directly to CPU for throttle back when needed.

Main features of bq25703A:

Charge 1- to 4-Cell Battery From Wide Range of Input Sources
3.5-V to 24-V Input Operating Voltage
Supports USB2.0, USB 3.0, USB 3.1 (Type C), and USB_PD Input Current Settings
Seamless Transition Between Buck and Boost Operation
Input Current and Voltage Regulation (IDPM and VDPM) Against Source Overload
Power/Current Monitor for CPU Throttling
Comprehensive PROCHOT Profile, IMVP8 Compliant
Input and Battery Current Monitor
System Power Monitor, IMVP8 Compliant
Narrow-VDC (NVDC) Power Path Management
Instant-On With No Battery or Deeply Discharged Battery
Battery Supplements System When Adapter is Fully-Loaded
Ideal Diode Operation in Supplement Mode
Power Up USB Port From Battery (USB OTG)
Output 4.48-V to 20.8-V Compatible With USB PD
Output Current Limit up to 6.35 A
800-kHz or 1.2-MHz Programmable Switching frequency for 1-μH to 2.2-μH Low Profile Inductor
Host Control Interface for Flexible System Configuration
I2C (bq25703A) Port for Optimal System Performance and Status Reporting
Hardware Pin to Set Input Current Limit Without EC Control
High Accuracy Regulation and Monitor
±0.5% Charge Voltage Regulation
±2% Input/Charge Current Regulation
±2% Input/Charge Current Monitor
±5% Power Monitor
Safety
Thermal Shutdown
Input, System, Battery Overvoltage Protection
MOSFET Inductor Overcurrent Protection
Low Battery Quiescent Current
Input Current Optimizer (ICO) to Extract Max Input Power
Charge Any Battery Chemistry: Li+, LiFePO4, NiCd, NiMH, Lead Acid
Package: 32-Pin 4 × 4 WQFN
bq25703A application:
• Drones, Bluetooth Speakers, IP Cameras, Detachable, and Tablet PCs and Power Bank
• Industrial and Medical Equipment
• Portable Equipment With Rechargeable Batteries

Figure 1. Functional block diagram of bq25703A

Figure 2. Typical application circuit diagram of bq25703A

Evaluation module bq2570x EVM (bq25700AEVM-732 and bq25703AEVM-732)

The bq25700AEVM-732 and bq25703AEVM-732 evaluation modules (EVM) are SMBus or I2C-controlledNVDC-1 buck boost charger. The input voltage range is between 3.5 V and 24 V, with a programmableoutput of 1–4 cells and a charge output current Range of 64 mA to 8.128 A. This EVM does not include theEV2400 interface device; the EV2400 must be ordered separately to evaluate the bq2570x EVM.

The bq2570x evaluation modules are complete charger modules for evaluating an SMBUS or I2Ccontrolledbuck boost charge using the bq2570x devices. The bq2570x EVM does not include the EV2400 interface board. To evaluate the bq2570x EVM, order anEV2400 interface board separately.

The bq2570x is a synchronous NVDC-1 battery buck boost charge controller, offering a low component count, high efficiency solution for space-constrained, multi-chemistry battery charging applications.

The NVDC-1 configuration allows the system to be regulated at the battery voltage, but not drop below the system minimum voltage. The system keeps operating even when the battery is completely discharged orremoved. When load power exceeds the input source rating, the battery supplement mode Prevent the input source from being overloaded. The bq2570x charges the battery from a wide range of input sources including a 5-V USB adapter to a high-voltage USB PD source and traditional adapters.

During power up, the charger sets the converter to buck, boost, or buck-boost configuration based on the input source and battery conditions. During the charging cycle, the charger automatically transits amongbuck, boost, and buck-boost configuration without host control.

The bq2570x monitors adapter current, battery current, and system power. The flexibly programmedPROCHOT output goes directly to the CPU for throttle back, when needed.